n. in linguistics, a function word that serves to conjoin two or more sentence constituents or sentences, the most common being and, as in John and Mary got married. Other common conjunctions include but, because, or, and if. See coordination.
n. any of several peptides that are released by neurons as neurotransmitters or neurohormones. They include the endogenous opioids (e.g., enkephalin, endorphin); peptides found in both the brain and the peripheral nervous system (e.g., substance P, neurotensin); hypothalamic releasing hormones (e.g., thyrotropin-releasing hormone); pituitary hormones (e.g., growth hormone, prolactin); and other circulating peptides (e.g., atrial natriuretic peptide, bradykinin).